U.S. Pat. No. 6,670,905, invented by the inventor named herein, and hereby incorporated by reference, discloses a GPS enabled radar detector that uses GPS to aid in the management of non-police-related or otherwise irrelevant sources of radar signals, permitting the detector to dynamically improve its handling of such sources and reduce false alerts. The detector references previously-stored geographically-referenced information on such sources, and compares the detector's current location to locations of known stationary false alert sources of radar to improve the handling of detection of those sources. When the detector is within a threshold distance of a stored false alert source, the detector suppresses alerts to frequency bands or sub-bands that correlate to the frequency of the known false alert source. False sources may be manually identified and “locked out” by the user, or may be automatically identified based upon multiple repeated encounters of the detector with the source at a particular geographic area.
Systems embodying the invention of the '905 patent have been successfully commercialized by the assignee of this application, and have proven commercially viable, but those systems remain subject to certain vulnerabilities which will be discussed herein.
One vulnerability is false radar alerts created by traffic sensing equipment installed in many major metropolitan areas. The signals from traffic sensors appear in police radar bands, and are emitted in short bursts at a regular cadence. Because traffic sensors are geographically fixed and operate in a consistent frequency range, it is possible for a radar detector user to manually lockout traffic sensor alerts; however, traffic sensor signals do not appear regularly enough to be reliably locked out automatically, at least without a greater than normal number of encounters. In response to this source of false signals, the assignee developed a Traffic Sensor Rejection (TSR) method, which searches for the characteristic cadence and frequency of traffic sensor systems, and suppresses alerts of those systems using a processing logic separate from the location-based lockout described in the '905 patent. Because this logic is separate from location based lockouts, police radar or police-like false signal sources appearing in the same frequency band and same geographic area as a TSR signal will not be suppressed by the TSR method, which is preferable to a location based frequency lockout in that area which would potentially suppress police signals as well.
Another vulnerability is the increasing number of vehicle-borne radar sources. Examples include radar based systems attached to vehicles for lane sensing, adaptive cruise control, collision prevention, automated parking, and the like, which will be collectively identified herein as “vehicle guidance systems”. One specific example of these systems is the Mercedes-Daimler Distronic system, which emits a 24.125 GHz K-band frequency to provide adaptive vehicle cruise control, which is in the band used by police and normally detected by a radar detector whenever it is near to an operative Distronic system. Vehicle guidance systems often create an annoying false alarm when a radar detector passes the source vehicle, and this false alarm cannot be suppressed based on location because the signal source is a mobile vehicle. The annoyance becomes critical when the vehicle with the radar detector is itself carrying a vehicle guidance system; the constant alerting in this scenario essentially puts the vehicle operator to a choice between disabling an entire band of radar detection (or foregoing radar detection entirely), and disabling the vehicle guidance system.
Efforts are underway by the assignee to identify characteristic cadences or other profiles of vehicle guidance systems, much as was done for TSR, and some have been effectively identified and suppressed via a separate methodology like that used for TSR. However, some vehicle guidance systems have so far eluded effective characterization in this manner.
A third vulnerability of the existing systems is that location based lockouts can potentially prevent alerting to police radar that happens to appear in the same frequency range and within a geographic range of a stationary source. As radar detectors become more sensitive the effective scope of a location lockout area must increase to ensure that alerts to the false signal are suppressed, which entails also increasing the geographic area in which alerts will be given to other sources in the same frequency ranges, including police radar sources. A regular criticism of location based lockout methods is the potential a radar detector will fail to alert to police radar which happens to coincide in location and frequency to a stored false signal. It would be desirable to improve the manner in which stationary false signals are processed to reduce the likelihood that an alert to actual police radar is suppressed.
A final vulnerability of the existing systems is the continuing adoption of ‘instant-on’ and line of site speed monitoring technology. A radar detector provides advance warning of police speed monitoring by detecting the monitoring of other cars that are typically ahead of the vehicle carrying the radar detector. Modern radar guns which operate in the Ka band can turn on and off rapidly, on a car-by-car basis. If there is a long enough interval between uses of the gun, a radar detector will not be able to pick up the stray radar emissions from previous interrogations to give advance warning of the use of radar. Laser (LIDAR) speed detection poses an even greater challenge for the reason that it is generally line of sight and provides very little advance warning of its use, if any. To respond to these challenges the assignee and others have developed social networks through which drivers can share radar events and sightings of police into a social network, so that a warning can be delivered to other drivers approaching the area. Unfortunately, users of social networks often report police activities that are not actually speed traps, for example, social network users may warn of a police car that is driving with traffic, waiting at a traffic light on a cross street, or involved in other activities that are not characteristic of a fixed location speed trap. Alerts that can be confirmed, e.g., via radar detection, are more reliable, but the social network cannot rely only upon radar-based alerts, for the reason that a police car on station at a speed trap may be using instant-on radar or LIDAR, in which case not every vehicle will be exposed to radar. Accordingly, it would be useful to provide a method for better identifying particular situations which are actually indicative of a speed trap, such as police positioned at a roadside monitoring passing traffic, or operating its light bar adjacent to a stopped car.